They soon let Kidd know their intention to buy Johanna for trafficking purposes, but Kidd protects the girl. Johanna and Kidd have no family. Johanna lost her original family when they were killed by the Kiowa tribe. The tribe then lost when the colonists murdered them.
Captain Kidd lost his family when his wife died and they had no children. Kidd and Johanna are also something of an outsider in this world, in general. Johanna isn't entirely German, she's not exactly Kiowa, and she's definitely not a Southerner. It's something in between, so it doesn't belong to any group.
Kidd is an older man who has some respect within the communities he reads stories to, but to others, he's a worthless old man, as evidenced by the way some people treat him. Throughout News of the World, Kidd's relationship with Johanna helps transform him into a man with something to worry about again. He sees Johanna not only as a challenge he is eager to overcome, but as an anxious and curious spirit that complements his own desire to share his knowledge with the rest of the world. Together they form at first an unlikely couple and then inseparable, until in the end she is a key part of their performances.
We don't know what awaits them in the future, but it is clear from the final scene of the film that Kidd is a changed man. One of the most interesting detours Kidd and Johanna take in News of the World is their trip to Erath County, Texas, which in 1870 was under the control of a corrupt businessman named Farley (Thomas Francis Murphy) who demands that Kidd read the news for his employees.